1. Field of the Invention
This invention relates generally to computer animation of three-dimensional scenes, and in particular to systems and methods for posing three-dimensional animated characters and/or other three-dimensional animated models that can be posed.
2. Background of the Invention
During the computer animation process, an animator often must pose one or more characters in a three-dimensional environment to create a scene. The current state of the art in posing three-dimensional characters usually involves a WIMP (windows, icons, menus, and pointers) interface combined with direct manipulation techniques. Direct manipulation techniques include a virtual trackball, described in Chen et al., “A Study in Interactive 3-D Rotation Using 2-D Control Devices,” SIGGRAPH 1988 Proceedings, p. 121-29; inverse kinematics, described in Girard et al., “Computational Modeling for the Computer Animation of Legged Figures,” SIGGRAPH '85 Proceedings, p. 263-70; and three-dimensional widgets, described in Snibbe et al., “Using Deformations to Explore 3D Widget Design,” SIGGRAPH 1992 Proceedings. The challenge for each of these techniques is to pose three-dimensional objects using a two-dimensional interface.
Existing methods may be satisfactory for artists highly familiar with computers and three-dimensional animation tools, but they can be quite daunting to two-dimensional artists unfamiliar with the three-dimensional medium. In the two-dimensional medium, artists typically sketch their drawings on paper. Regardless of their medium of choice, many animators use gesture drawings or small “thumbnail sketches” to work out their poses before embarking on the more laborious task of drawing the entire character in detail. A gesture drawing is a quick sketch—usually made in a few seconds—that conveys the attitude or essence of a pose without necessarily depicting the subject precisely. Beneficially, a gesture drawing reduces a complex subject to simple shapes that are easy to draw.
As the animation industry expands from traditional hand-drawn methods into digital production and three-dimensional animation, there is a need to retrain talented two-dimensional animators to work in this new medium. Currently, to make this transition, artists must first master an unfamiliar three-dimensional interface paradigm. It would be better if instead artists were given an interface that builds on the drawing skills they already have. Even for artists already familiar with three-dimensional animation, such an interface might prove a natural and comfortable alternative or supplement to existing methods.